ESTIMATION OF HETEROSIS AND GENETIC PARAMETERS FOR SOME FLOWERING AND VEGETATIVE TRAITS IN MAIZE USING THE DIALLEL CROSS METHOD

A diallel cross among inbred lines of maize (Zea mays L.) with medium maturity and an evaluation to estimate the genetic parameters for days to 50 % tasseling, days to 50% silking, plant and ear heights, resistance to late wilt disease, ear position were carried out. Mean squares were significant for all of the studied traits. Hybrids mean squares were highly significant for the all studied traits under both planting dates and combined analysis, except days to 50% silking. Indicating that the hybrids performance differed from planting date to another. The highest negative heterosis effect was exhibited by cross P5×P2, P6×P2, P2×P6, P3×P5and P3×P6 over better parent, crosses P5×P2 , P6×P2 and P2×P6 over mid- parents and crosses P5×P1, P3×P2 , P4×P2 ,P5×P2 , P6×P2 , P2×P6 , P3×P5 and P3×P6 over check varieties for tasseling date. For days to 50% silking showed that highest significant and negative heterotic effect was exhibited by crosses P6×P1, P6×P2, P2×P6, P4×P3 and P3×P6 over mid- parents and all crosses had highly significant and negative heterosis over check varieties, the highest significant and negative heterotic effects were reported by P6×P1, P6×P2, P2×P6, P4×P3 and P3×P6 over mid- parents and, P3×P2, P4×P2 reciprocal, P5×P2, P6×P2 and P3×P6 over check varieties, The highest significant and positive heterotic effect was exhibited by P3×P5 and P4×P3 (40.35 and 37.46%) over better-parent and mid-parents respectively, P4×P2 (13.93%) highest negative significant heterotic effect over check varieties for plant height. For ear height cross P4×P3 showed maximum negative heterosis over check varieties. For resistance to late wilt disease results regarding significant for crosses P1×P3,P3×P1,P1×P4 ,P4×P1,P1×P5 and P5 x P1 (1.522%) over mid-parents , indicating that these crosses are the best combinations for resistance to late wilt disease. For ear position , 25 crosses show highly significant and negative heterosis over better-parent value for ear position ,P4×P3 showed maximum negative heterosis over better-parent and over mid-parents . Seven crosses show highly significant and negative heterosis over check varieties value for ear position, P6×P4 (-8.92%) showed maximum negative heterosis over check varieties. Heritability estimates in broad sense were generally higher at combined data. In the combined data percentage of heritability in the narrow sense for studied traits ranged from 20% for plant height to 46% for days to 50% tasseling or silking. Heritability estimates were low for plant and ear heights in narrow sense (20% and 28%) and the same in broad sense (29% and 38%), respectively. Heritability estimates in broad sense were medium (29% -64%) of all studied traits. Hence it could be concluded that these crosses may be useful for improving maize grain yield program.